1. Field of the Invention
The present invention relates to a semiconductor manufacturing device, and more particularly to a semiconductor inspecting device or a semiconductor exposure device equipped with a mechanical drive part for moving, or rotating and tilting a substrate, such as a semiconductor substrate or a glass substrate, within a vacuum device while holding the substrate.
2. Description of the Prior Art
Accompanying a rapid advancement in the refinement of the minimum dimension of semiconductor devices from 0.13 μm to 0.10 μm or less, an electron beam exposure device or an X-ray exposure device has become to be adopted for lithography process, and the semiconductor substrate is being subjected to exposure process in a vacuum atmosphere. Besides, in a semiconductor inspection device, apparatuses employing electron beams or X-rays are being introduced in order to enhance the spatial resolution.
One item common to these semiconductor devices is that in both cases the stage portion holding the substrate is moved, or rotated or tilted as may be needed, in a vacuum atmosphere. The most serious problem in the manufacturing process or the inspection process is deterioration in the yield due to generation of defective products caused by the attachment of molecular or clustered chemical substances to the surface of the substrate in such a process.
A means of solving the problem is to absolutely block the attachment of the molecular or clustered chemical substances to the substrate in the manufacturing or the inspection process.
Now, when an oil diffusion pump is used in the vacuum evacuation system, oil components diffuse backward from the pump to the reaction chamber and attach to the substrate by such actions as the divergence of oil vapor, re-evaporation of condensed oil from the inner wall of the cylinder, and evaporation of the lighter components due to thermal decomposition of oil. Moreover, if grease with high volatility is used, components with high vapor pressure existing in the grease evaporate in the vacuum atmosphere, and attach themselves to the surface of the substrate. For these reasons, in the conventional semiconductor manufacturing device or semiconductor inspection device having a mechanical drive part for moving, or rotating or tilting a semiconductor substrate or a glass substrate in a vacuum device, employment of a pump with smaller amount of used oil or use of grease with lower vapor pressure, or the like has been devised so as to block the attachment of the chemical substances, and has been considered that a sufficient effect has been achieved.
The advancement of refinement of semiconductor elements has drastically changed the semiconductor manufacturing processes, and as a result, the methods which have been adopted in the past, namely, the use of a pump with smaller amount of oil and the use of grease with lower vapor pressure, are being proven to be no longer sufficient. This is because, in view of the current technical common knowledge that the permissible amount of impurities attaching to the surface of the substrate in the semiconductor manufacturing process is limited to below about 1×1010[atoms/cm2], hydrocarbon based substances which are the principal components of the grease that attach themselves to the surface of the substrate is in an amount beyond the allowable amount mentioned above, in a vacuum device using a representative grease (for example, grease having the vapor pressure of 0.6 Torr at 200° C.).
Attachment of such oil and grease components to the surface of the substrate causes a serious problem of degradation in the product yield. For example, there is generated a pattern defect due to nonuniform coating of a photo resist in the plane of the wafer when the photo resist is spin coated, or there is caused a pattern defect called residue due to nonuniform etching of the plane of the wafer in the etching process. In addition, amine component in the molecular or clustered chemical substances attached to the surface of the substrate may cause a pattern defect by affecting the photochemical reaction of the photo resist.
In any case, as a result of a drastic increase in the number of semiconductor manufacturing processes of a semiconductor manufacturing device that employs electron beams or X rays, and a drastic increase in the number of the so-called in-line inspection processes that return the substrates after inspection that uses a semiconductor inspection device employing electron beams or X rays, attachment of molecular or clustered chemical substances to the surface of the substrates has become to seriously affect the deterioration in the yield of the products.
However, it is impossible not to introduce grease which is a supply source of molecular or clustered chemical substances to the surface of the substrate into the semiconductor manufacturing device or the semiconductor inspection device having a mechanical drive part for moving, or rotating or tilting the semiconductor substrate or the glass substrate within the device. The reason for this is that the use of grease which plays the role of a lubricant or a cooling material is indispensable in order to provide a high accuracy of stopping position to the mechanical drive part that holds the semiconductor substrate or the glass substrate.
As an attempt to solve this problem a method is proposed to heat the semiconductor substrate prior to semiconductor substrate processing in the vacuum device or following the processing of the semiconductor substrate (Japanese Patent Applications Laid Open, No. H5-55330. This method is based on the idea of evaporating the molecular or clustered chemical substances attached once to the surface of the semiconductor substrate, namely, to return the surface of the semiconductor substrate contaminated once to clean state again by subjecting the semiconductor substrate to heating.
However, in order to eliminate the degradation in the yield of the products due to the employment of a semiconductor manufacturing device or a semiconductor inspection device that employs electron beams or X rays, it is necessary to absolutely exclude the attachment of molecular or clustered chemical substances to the surface of the semiconductor substrate within the semiconductor manufacturing device or the semiconductor inspection device, from the beginning to the end of the processing procedures.